[rfc] Avoid failure when compiler is wrapped.

[Andrew Hughes]

----- Original Message -----
> On 2016-01-25 21:38, Andrew Hughes wrote:
> > ----- Original Message -----
> >> Hello!
> >>
> >> When compiler is wrapped, the configure phase of build fails:
> >>
> >> [...]
> >> checking for gcc... /usr/lib64/cscppc/gcc
> >> configure: Resolving CC (as /usr/lib64/cscppc/gcc) failed, using
> >> /usr/lib64/cscppc/gcc directly.
> >> checking resolved symbolic links for CC... /usr/bin/cscppc
> >> checking if CC is disguised ccache... no, keeping CC
> >> configure: The C compiler (located as /usr/bin/cscppc) does not seem to be
> >> the required GCC compiler.
> >> configure: The result from running with --version was: "Usage:"
> >> configure: error: GCC compiler is required. Try setting --with-tools-dir.
> >> configure exiting with result code 1
> >>
> >>
> >>   From time to time I'm building RPMS for fedora  with wrapped compiler to
> >>   be
> >>   able to investigate C
> >> code changes. Added is patch, which is allowing to walk around the issue.
> >>
> >> I'm wondering if this is still desired behaviour. or if it can be better
> >> iff-ed out to be by default
> >> on, but eg only disablef on AIX.
> >>
> >> CCed is Andrew, who is facing similar issue on Gentoo.
> >>
> >>
> >>     Thanx!
> >>     J.
> >>
> > The Gentoo issue was different; it's related to distcc failing the version
> > test, rather than symlink issues.
> >
> > I think this block should be removed, not just comment out, if not needed.
> > But first, I think we need to know why the dereferencing is there.
> > Can someone at Oracle shed some light on this?
> 
> Maybe a glow of twilight. :) This check was added quite early in the new
> build system and was included in the original integration of the new
> build system into mainline. I remember vaguely that we had issues with
> some machines with strange setups which turned out to have unexpected
> symlinks. So we thought it was better to clearly show in the configure
> log which compiler *really* was used.
> 
>  From the hg history, I also see that about a year ago, I added this
> comment in JDK-8034788:
>   # FIXME: This test should not be needed anymore; we don't do that for
> any platform.
> 
> So maybe we should live up to that fixme, and remove the check. :-)
> 
> I just realized that we can still keep ability to debug broken systems
> by resolving the symlink, but just printing the result and not modifying
> the path to the CC we will use. I opened
> https://bugs.openjdk.java.net/browse/JDK-8148351 for this.

Thanks for the feedback. I can understand why it was added. Simple verbosity
at appropriate points can help debug a lot of these configuration issues.

Should I go ahead and create a patch for this or are you already working on
it? An AC_MSG_NOTICE or AC_MSG_WARNING seems sufficient to help debug broken
systems.

> 
> /Magnus
> 

-- 
Andrew :)

Senior Free Java Software Engineer
Red Hat, Inc. (http://www.redhat.com)

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